1. Field of the Invention
The invention relates to a hood structure of a motor vehicle. More particularly, the invention relates to a motor vehicle hood structure that moves a hood to such a position as to effectively absorb impact energy exerted on a colliding body.
2. Description of the Related Art
A hood structure of a motor vehicle that moves a hood to such a position as to effectively absorb impact energy exerted on a colliding body is described in Japanese Patent Application Laid-Open Publication No. 2000-79859.
As shown in FIG. 17, this hood structure of a motor vehicle includes a pedestrian detection means 100 for detecting collision with a pedestrian or the like, a controller 102 that determines whether to actuate a system upon receiving a signal from the pedestrian detection means 100, a lift mechanism 108 that lifts a rearward portion of a hood 106 if the controller 102 determines that an air bag body 104 needs to be deployed, and an air bag device 110 that inflates and deploys the air bag body 104 after actuation of the lift mechanism 108 has started. The air bag device 110 is disposed below a rearward portion of the hood 106. The air bag body 104 of the air bag device 110 has a partition wall 112 that restricts the maximum distance between a bag's lower wall surface and a bag's upper wall surface, at an intermediate portion in the air bag body 104 in an inflated and deployed state in a longitudinal direction relative to the vehicle, so that when inflated and deployed, the air bag 104 contacts an area in a lower surface of a rearward portion of the hood 106 in a lifted-up state, the area extending over substantially the entire width of the hood 106 in a transverse direction relative to the vehicle, and is exposed rearward of a rear end of the hood 106.
This hood structure of a motor vehicle is constructed so that when collision with a pedestrian or the like is detected, a rearward portion of the hood 106 is lifted with a front portion of the hood 106 being a center of the lifting motion, by the lift mechanism 108. Therefore, if the hood is elongated in the longitudinal direction relative to the vehicle, the amount of lift of a rearward portion of the hood 106 needs to be substantially great in order to secure a load absorption stroke of a longitudinal-direction central portion 106A of the hood 106. Hence, it is difficult to achieve a great amount of lift of the longitudinal-direction central portion of the hood 106 while reducing the hood lift-up time to a predetermined value. As a result, the hood structure has a drawback of a short stroke of load absorption of the longitudinal-direction central portion 106A of the hood 106.